Here's the problem: http://i.imgur.com/dS7ZH.jpg(adsbygoogle = window.adsbygoogle || []).push({});

I don't understand why the cosine has to be there. My geometry is a bit rusty, but wouldn't it be enough without the cosine part?

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Basic electrostatics (geometry help)

**Physics Forums | Science Articles, Homework Help, Discussion**